Current knowledge of vector-borne zoonotic pathogens in Zambia: A clarion call to scaling-up "One Health" research in the wake of emerging and re-emerging infectious diseases

A review of the mosquito-borne flaviviruses: Dengue virus and West Nile virus in Southern Africa

Dengue virus (DENV) and West Nile (WNV) viruses are important re-emerging mosquito-borne members of the genus Flavivirus that are under-recognized in many parts of Africa. This review aims to evaluate the existing literature on the transmission, epidemiology, diagnostic techniques, clinical presentation and prevention of infection with DENV and WNV in Southern Africa. Literature shows that both DENV and WNV are transmitted by mosquitoes of Aedes spp. and Culex species., respectively, and both viruses are widespread in the Southern African region. Epidemiologically, sporadic outbreaks have been reported of both DENV and WNV in various Southern African countries, indicating the ongoing threat of these viruses. However, the lack of comprehensive surveillance and diagnostic capacity challenges accurate estimation of their true prevalence. Diagnostic techniques for DENV and WNV involve serological tests, molecular tests and viral isolation, enabling prompt diagnosis and differentiation from other febrile illnesses. In Southern Africa, infection with DENV and WNV presents significant public health concerns, with the clinical presentation of both infections ranging from asymptomatic cases to severe manifestations. Symptoms of infection include high fever, myalgia, rash, and, in severe cases, haemorrhagic fever for DENV and neurological complications for WNV. No specific antiviral treatment exists for either virus, underscoring the importance of supportive care and symptom management. To prevent the spread of DENV and WNV in Southern African countries, a combination of prevention and treatment strategies should be employed, including effective mosquito control, continuous monitoring of vector population dynamics, public health education, and surveillance and reporting systems for averting future outbreaks.

A Comprehensive Review: Biology of Anopheles squamosus, an Understudied Malaria Vector in Africa

With ongoing global efforts to eliminate malaria, several countries have entered a pre-elimination stage, in which populations of the primary mosquito vector are reduced and the rates of malaria transmission are low. Efforts to eliminate malaria have changed the dynamics of disease transmission, causing a shift in anopheline community composition in some regions. One of the most abundant species of Anopheles found in pre-elimination areas, such as southern Africa, is Anopheles squamosus (Theobald, 1901; Diptera: Culicidae). Although An. squamosus has been documented across the African continent, limited information is available about its biology. Knowing what, when, and where the malaria vector bites humans can help develop effective malaria control strategies. The aim of this review is to compile the information available on An. squamosus's biology, ecology, distribution, behavior, and potential role in disease transmission. The review of current literature suggested that An. squamosus is abundant throughout the African continent. Studies indicate that this species occupies the same range and exhibits similar behaviors to primary malaria vectors in southern and eastern African countries, like Zambia. In conclusion, An. squamosus continues to be an understudied species that has circumvented disease control measures and further studies are needed to develop effective control strategies.

Knowledge of Human Monkeypox Virus Infection among Healthcare Providers and Associated Factors in Addis Ababa, Ethiopia

Human monkeypox virus infection (mpox) is a reemerging viral zoonotic disease that has been occurring outside of locations where it has been endemic in Africa. To understand the shifting epidemiology of this disease and respond accordingly, increased clinical skill and professional capabilities are essential. However, there are no studies assessing the knowledge of healthcare professionals in Ethiopia on mpox. Hence, this paper aimed to assess knowledge of the infection and associated factors among healthcare providers in Addis Ababa, Ethiopia, specifically knowledge of diagnosis and treatment of mpox, from November 14, 2022 to November 25, 2022. A facility-based cross-sectional study design was used. Knowledge was assessed using a structured questionnaire, and a 70% Bloom's cutoff point was used to classify the scores. A pretest was conducted in a similar setting before data collection. Frequencies, percentages, and bivariate and multivariate logistic regression analyses were used. The majority of participants, 128 (64.6% with 95% CI), scored below 70% on knowledge questions. Professionals with experience of 5 years or less had better knowledge than those who had worked longer (adjusted odds ratio: 0.301; 95% CI: 0.149-0.609; P = 0.000). Knowledge of mpox among healthcare providers in Addis Ababa was poor across sociodemographic and professional variables. Thus, education on mpox among healthcare providers in Ethiopia is critical in preparing the workforce and limiting potential damage to the country.

Molecular detection and phylogenetic characterization of Rickettsia in ticks collected from leopard tortoise (Geochelone pardalis) in rural Zambia

In sub-Saharan Africa, limited studies have investigated zoonotic pathogens that may be harboured by ticks infesting reptiles such as tortoises. Here, we report the presence of pathogenic Rickettsia in ticks (Amblyomma marmoreum) collected from the leopard tortoise (Geochelone pardalis) in rural Zambia. Using polymerase chain reaction, 56% (49/87) of ticks were positive for the Rickettsia outer membrane protein (ompB) gene. Multi-locus sequence and phylogenetic analysis based on the ompB, ompA, and citrate synthase (gltA) genes showed that the ticks carried R. africae, and other Rickettsia spp. closely related to R . raoultii, R . massiliae, R . tamurae and R . monacensis. Given the proximity between humans, livestock, and wildlife in these habitats, there exists a considerable risk of transmission of zoonotic Rickettsia to human populations in this rural setting. These results call for heightened awareness and further research into the dynamics of tick-borne diseases in regions where humans and animals coexist, particularly in the context of tortoise-associated ticks as vectors. Understanding and addressing these potential disease vectors is crucial for effective public health measures and the prevention of Rickettsia zoonoses.

The elimination of human African trypanosomiasis: Monitoring progress towards the 2021-2030 WHO road map targets

BACKGROUND

Human African trypanosomiasis (HAT) is a neglected tropical disease that usually occurs in rural areas in sub-Saharan Africa. It caused devastating epidemics during the 20th century. Sustained, coordinated efforts by different stakeholders working with national sleeping sickness control programmes (NSSCPs) succeeded in controlling the disease and reducing the number of cases to historically low levels. In 2012, WHO targeted the elimination of the disease as a public health problem by 2020. This goal has been reached and a new ambitious target was stated in the WHO road map for NTDs 2021-2030 and endorsed by the 73rd World Health Assembly: the elimination of gambiense HAT transmission (i.e. reducing the number of reported cases to zero). The interruption of transmission was not considered as an achievable goal for rhodesiense HAT, as it would require vast veterinary interventions rather than actions at the public health level.

METHODOLOGY/PRINCIPAL FINDINGS

Data reported to WHO by NSSCPs were harmonized, verified, georeferenced and included in the atlas of HAT. A total of 802 cases were reported in 2021 and 837 in 2022. This is below the target for elimination as a public health problem at the global level (< 2000 HAT cases/year); 94% of the cases were caused by infection with T. b. gambiense. The areas reporting ≥ 1 HAT case/10 000 inhabitants/year in 2018-2022 cover a surface of 73 134 km2, with only 3013 km2 at very high or high risk. This represents a reduction of 90% from the baseline figure for 2000-2004, the target set for the elimination of HAT as a public health problem. For the surveillance of the disease, 4.5 million people were screened for gambiense HAT with serological tests in 2021-2022, 3.6 million through active screening and 0.9 million by passive screening. In 2021 and 2022 the elimination of HAT as a public health problem was validated in Benin, Uganda, Equatorial Guinea and Ghana for gambiense HAT and in Rwanda for rhodesiense HAT. To reach the next goal of elimination of transmission of gambiense HAT, countries have to report zero cases of human infection with T. b. gambiense for a period of at least 5 consecutive years. The criteria and procedures to verify elimination of transmission have been recently published by WHO.

CONCLUSIONS/SIGNIFICANCE

HAT elimination as a public health problem has been reached at global level, with seven countries already validated as having reached this goal. This achievement was made possible by the work of NSSCPs, supported by different public and private partners, and coordinated by WHO. The new challenging goal now is to reach zero cases by 2030. To reach this goal is crucial to maintain the engagement and support of donors and stakeholders and to keep the involvement and coordination of all partners. Along with the focus on elimination of transmission of gambiense HAT, it is important not to neglect rhodesiense HAT, which is targeted for elimination as a public health problem in the WHO road map for NTDs 2021-2030.

Advancing Chikungunya Diagnosis: A Cost-Effective and Rapid Visual employing Loop-mediated isothermal reaction

The diagnosis of Chikungunya (CHIKV), along with the simultaneous monitoring of virus circulation in the population or vectors, is essential for global health. Although effective diagnostic methods for CHIKV, such as RT-qPCR, exist, their utilization is constrained by high costs. With the aim of contributing to the field of diagnostics, we have developed a diagnostic assay using isothermal amplification technology with visually interpretable results. This test can detect the virus within a maximum timeframe of 30 minutes. The detection limit of RT-LAMP CHIKV was found to be 66 copies of RNA molecules (Ct ≅ 31.28), and no cross-reactivity with other arboviruses was observed. During test validation, our assay demonstrated a sensitivity of 80.43%, specificity of 100%, and an overall accuracy of 88.89%. By utilizing more cost-effective reagents and equipment compared to RT-qPCR, this test holds the potential for broader application and enhanced accessibility, particularly in point-of-care settings.

Community perceptions, acceptability, and the durability of house screening interventions against exposure to malaria vectors in Nyimba district, Zambia

BACKGROUND

House screening remains conspicuously absent in national malaria programs despite its recognition by the World Health Organization as a supplementary malaria vector-control intervention. This may be attributed, in part, to the knowledge gap in screen durability or longevity in local climatic conditions and community acceptance under specific cultural practices and socio-economic contexts. The objectives of this study were to assess the durability of window and door wire mesh screens a year after full house screening and to assess the acceptability of the house screening intervention to the participants involved.

METHODS

This study was conducted in Nyimba district, Zambia and used both quantitative and qualitative methods of data collection and analysis. Both direct observation and questionnaires were employed to assess the durability of the screens and the main reasons for damage. Findings on damage were summarized as percentages. Focus group discussions were used to assess people's knowledge, perceptions, and acceptability of the closing eaves and house screening intervention. Deductive coding and inductive coding were used to analyse the qualitative data.

RESULTS

A total of 321 out of 400 (80.3%) household owners of screened houses were interviewed. Many window screens (90.3%) were intact. In sharp contrast, most door screens were torn (n = 150; 46.7%) or entirely removed (n = 55; 17.1%). Most doors (n = 114; 76%) had their wire mesh damaged or removed on the bottom half. Goats (25.4%), rust (17.6%) and children (17.1%) were cited most as the cause of damage to door screens. The focus group discussion elicited positive experiences from the participants following the closing of eaves and screening of their windows and doors, ranging from sleeping peacefully due to reduced mosquito biting and/or nuisance and having fewer insects in the house. Participants linked house screening to reduced malaria in their households and community.

CONCLUSION

This study demonstrated that in rural south-east Zambia, closing eaves and screening windows and doors was widely accepted. Participants perceived that house screening reduced human-vector contact, reduced the malaria burden and nuisance biting from other potentially disease carrying insects. However, screened doors are prone to damage, mainly by children, domestic animals, rust, and termites.

T Lymphocyte Interferon-gamma Response to Anaplasmataceae-related Major Surface Proteins and Ankyrin A in Fibromyalgia

BACKGROUND

The aetiology of fibromyalgia is unknown; its symptoms may be related to a T-lymphocyte-mediated response to infectious organisms.

OBJECTIVES

First, to test the hypothesis that fibromyalgia is associated with increased interferon (IFN)-γ-secreting T-lymphocytes after stimulation with Anaplasmataceae-related major surface proteins (MSPs) and the macromolecular translocation type IV secretion system effector ankyrin repeat domain-containing protein A (AnkA). Second, to ascertain the relationship in fibromyalgia between (i) the IFN-γ-secreting T-lymphocyte response to stimulation with Anaplasmataceae-related MSPs and AnkA, and (ii) co-infection by Borrelia and Yersinia spp., and antinuclear antibodies.

METHODS

Using a case-control design, patients fulfilling the American College of Rheumatology revised criteria for fibromyalgia, and controls, underwent the following blinded assessments: (i) enzyme- linked immune absorbent spot (ELISpot) IFN-γ release assay of T-lymphocyte reactivity to Anaplasmataceae-related MSPs and AnkA; (ii) ELISpot IFN-γ release assays of T-lymphocyte reactivity to three Borrelia antigens, namely Borrelia burgdorferi full antigen (B31); peptide mix (from Borrelia burgdorferi sensu stricto, Borrelia afzelii, Borrelia garinii); and Borrelia burgdorferi lymphocyte function-associated antigen-1; (iii) immunoglobulin (Ig) A assay by enzyme-linked immunosorbent assay (ELISA) of antibodies to Yersinia spp.; (iv) IgG (ELISA) antibodies to Yersinia spp.; (v) serum antinuclear antibodies (immunofluorescence).

RESULTS

The groups were age- and sex-matched. The mean (standard error) value of IFN-γ release for the fibromyalgia group was 1.52 (0.26), compared with 1.00 (0.22) for the controls. Generalised linear modelling (p<0.001) of IFN-γ release in the fibromyalgia patients showed significant main effects of all three indices of Borrelia infection and of antinuclear antibodies.

CONCLUSION

Anaplasmataceae may play an aetiological role in fibromyalgia.

Expanding diversity of bunyaviruses identified in mosquitoes

Mosquitoes interact with various organisms in the environment, and female mosquitoes in particular serve as vectors that directly transmit a number of microorganisms to humans and animals by blood-sucking. Comprehensive analysis of mosquito-borne viruses has led to the understanding of the existence of diverse viral species and to the identification of zoonotic arboviruses responsible for significant outbreaks and epidemics. In the present study on mosquito-borne bunyaviruses we employed a broad-spectrum RT-PCR approach and identified eighteen different additional species in the Phenuiviridae family and also a number of related but unclassified bunyaviruses in mosquitoes collected in Zambia. The entire RNA genome segments of the newly identified viruses were further analyzed by RNA sequencing with a ribonuclease R (RNase R) treatment to reduce host-derived RNAs and enrich viral RNAs, taking advantage of the dsRNA panhandle structure of the bunyavirus genome. All three or four genome segments were identified in eight bunyavirus species. Furthermore, L segments of three different novel viruses related to the Leishbunyaviridae were found in mosquitoes together with genes from the suspected host, the Crithidia parasite. In summary, our virus detection approach using a combination of broad-spectrum RT-PCR and RNA sequencing analysis with a simple virus enrichment method allowed the discovery of novel bunyaviruses. The diversity of bunyaviruses is still expanding and studies on this will allow a better understanding of the ecology of hematophagous mosquitoes.

Detection of Hemopathogens in Chelonoidis carbonaria: Microscopic, Molecular, Hematological, and Clinical Biochemistry Aspects

Background: The growing contact between men and wild animals, caused by the increase in the population in urban centers and the destruction of the habitat of these animals, has been leading to a greater circulation of pathogens between humans and wildlife. Chelonoidis carbonaria, a tortoise found throughout South America, is one of the animals most rescued from animal trafficking and illegal breeding. Considering this situation, this study aimed to verify the occurrence of hemoparasites in C. carbonaria. Materials and Methods: Blood samples from 73 C. carbonaria were collected from animals located in (1) a rural commercial breeding unit, (2) an urban zoo, and (3) a center of rescued animal screening. Genomic DNA was extracted from these animals and used in PCRs to detect specific genomic fragments of haemogregarines (i.e., Hepatozoon and Hemolivia), and members of the Anaplasmataceae Family (i.e., Ehrlichia sp. and Anaplasma sp.). Blood samples were screened for hemopathogens by direct microscopy and were used for hematological assays, and serum samples were analyzed to determine the concentration of serum components. Results: It was found that 34.2% of the tortoises presented Sauroplasma sp. in their blood samples; these animals showed clinical biochemistry changes that indicate altered liver function. Two zoo animals were positive for Ehrlichia sp. in PCR, and also presented clinical biochemistry and hematological changes. Conclusion: The present project is pioneer in the detection of Ehrlichia sp. in C. carbonaria, and was able to identify changes in clinical biochemistry that can be a result of the infection by hemopathogens in this species.

Ecological Niche Modeling of Aedes and Culex Mosquitoes: A Risk Map for Chikungunya and West Nile Viruses in Zambia

The circulation of both West Nile Virus (WNV) and Chikungunya Virus (CHIKV) in humans and animals, coupled with a favorable tropical climate for mosquito proliferation in Zambia, call for the need for a better understanding of the ecological and epidemiological factors that govern their transmission dynamics in this region. This study aimed to examine the contribution of climatic variables to the distribution of Culex and Aedes mosquito species, which are potential vectors of CHIKV, WNV, and other arboviruses of public-health concern. Mosquitoes collected from Lusaka as well as from the Central and Southern provinces of Zambia were sorted by species within the Culex and Aedes genera, both of which have the potential to transmit viruses. The MaxEnt software was utilized to predict areas at risk of WNV and CHIKV based on the occurrence data on mosquitoes and environmental covariates. The model predictions show three distinct spatial hotspots, ranging from the high-probability regions to the medium- and low-probability regions. Regions along Lake Kariba, the Kafue River, and the Luangwa Rivers, as well as along the Mumbwa, Chibombo, Kapiri Mposhi, and Mpika districts were predicted to be suitable habitats for both species. The rainfall and temperature extremes were the most contributing variables in the predictive models.

Investigating and combatting the key drivers of viral zoonoses in Africa: an analysis of eight epidemics

Investigating the interplay of factors that result in a viral zoonotic outbreak is difficult, though it is increasingly important. As anthropogenic influences shift the delicate balance of ecosystems, new zoonoses emerge in humans. Sub-Saharan Africa is a notable hotspot for zoonotic disease due to abundant competent mammalian reservoir hosts. Furthermore, poverty, corruption, and an overreliance on natural resources play considerable roles in depleting biological resources, exacerbating the population's susceptibility. Unsurprisingly, viral zoonoses have emerged in Africa, including HIV/AIDS, Ebola, Avian influenza, Lassa fever, Zika, and Monkeypox. These diseases are among the principal causes of death in endemic areas. Though typically distinct in their manifestations, viral zoonoses are connected by underlying, definitive factors. This review summarises vital findings on viral zoonoses in Africa using nine notable case studies as a benchmark for future studies. We discuss the importance of ecological recuperation and protection as a central strategy to control zoonotic diseases. Emphasis was made on moderating key drivers of zoonotic diseases to forestall future pandemics. This is in conjunction with attempts to redirect efforts from reactive to pre-emptive through a multidisciplinary "one health" approach.

Ticks, Fleas, and Harboured Pathogens from Dogs and Cats in Cyprus

Ticks and fleas are blood-sucking ectoparasites that cause irritation and anaemia to their hosts and act as vectors of pathogens (vector-borne pathogens, VBPs) of relevance for animal and human health. In the present study, tick and flea species in dogs and cats from Cyprus were recorded and VBPs were detected in the collected specimens. Ectoparasites were collected from 220 animals (161 dogs and 59 cats), and a questionnaire including demographic, clinical, and other information was filled out for each animal. The ectoparasites were morphologically identified and the detection of VBPs was performed by PCR-coupled sequencing. Rhipicephalus sanguineus sensu lato was found on 108 dogs and 13 cats, and Ixodes gibbosus on 2 dogs. Ctenocephalides felis was the predominant flea species (on 62 dogs and 45 cats), while one dog and one cat were infested by Ctenocephalides canis and Echidnophaga gallinacea, respectively. The VBPs in ticks were Anaplasma platys, Rickettsia massiliae, Rickettsia conorii, Rickettsia felis, Hepatozoon felis and Hepatozoon canis, while Rickettsia felis, Rickettsia sp., Bartonella koehlerae, Bartonella clarridgeiae, and Bartonella henselae were recorded in fleas. Statistical analysis (chi-square test and multiple univariate generalized linear model) showed that animals up to 6 months of age were less likely to be infested with ticks than older animals, but more likely to be infested with fleas. Ticks were more prevalent in sheltered than in owned animals, while the odds ratio of flea presence was higher in owned animals than those living in shelters. The present study is the first investigation on the occurrence of ticks and fleas in dogs and cats from Cyprus, showing the presence of different VBPs in these important ectoparasites. The results point out the importance of systematic ectoparasite control in dogs and cats.

Epidemiological compatibility of Amblyomma sculptum as possible vector and Panthera onca as reservoir of Cytauxzoon spp. in Midwestern Brazil

Cytauxzoonosis is an acute and highly lethal tick-borne disease of wild and domestic cats, and is widely distributed in Africa, Asia, Europe, the USA and Brazil. So far, only two tick species present on the USA are experimentally confirmed in Cytauxzoon transmission however, in Brazil and other continents, the epidemiology of the disease remains unknown. Evidences points to Panthera onca as a possible reservoir, but there is no evidence to point the vector. Therefore, this study evaluates the presence of Cytauxzoon spp. in wild felids from areas with and without records of Amblyomma sculptum this ixodid for comparison. Overall, 53 blood samples of P. onca, Puma concolor, and Leopardus pardalis from the Midwest region (MR; region with A. sculptum) and 143 blood and/or spleen samples from Leopardus geoffroyi, Leopardus wiedii, Leopardus munoai, Leopardus guttulus, Herpailurus yagouaroundi, L. pardalis, and P. concolor from Rio Grande do Sul State (RS; without A. sculptum). Only one feline sample was negative for Cytauxzoon sp. from MR; no samples from RS were positive. In total, 507 ticks were identified from MR felids, with predominance of A. sculptum (69.23%). In RS, there were 93 ixodids, of which 90.32% were Amblyomma aureolatum. The difference in the tick fauna of the two regions studied (presence/absence of A. sculptum) reflects the results found. This study highlighted A. sculptum as a possible vector since this hemoparasite was abundantly observed in areas where it occurs, also, there was no evidence of Cytauxzoon spp. where it was absent. Additionally, the study supported the suggestion that P. onca is the reservoir for the agent in MR.

Green Nano-Biotechnology: A New Sustainable Paradigm to Control Dengue Infection

Dengue is a growing mosquito-borne viral disease prevalent in 128 countries, while 3.9 billion people are at high risk of acquiring the infection. With no specific treatment available, the only way to mitigate the risk of dengue infection is through controlling of vector, i.e., Aedes aegypti. Nanotechnology-based prevention strategies like biopesticides with nanoformulation are now getting popular for preventing dengue fever. Metal nanoparticles (NPs) synthesized by an eco-friendly process, through extracts of medicinal plants have indicated potential anti-dengue applications. Green synthesis of metal NPs is simple, cost-effective, and devoid of hazardous wastes. The recent progress in the phyto-synthesized multifunctional metal NPs for anti-dengue applications has encouraged us to review the available literature and mechanistic aspects of the dengue control using green-synthesized NPs. Furthermore, the molecular bases of the viral inhibition through NPs and the nontarget impacts or hazards with reference to the environmental integrity are discussed in depth. Till date, major focus has been on green synthesis of silver and gold NPs, which need further extension to other innovative composite nanomaterials. Further detailed mechanistic studies are required to critically evaluate the mechanistic insights during the synthesis of the biogenic NPs. Likewise, detailed analysis of the toxicological aspects of NPs and their long-term impact in the environment should be critically assessed.

An unusually long Rift valley fever inter-epizootic period in Zambia: Evidence for enzootic virus circulation and risk for disease outbreak

Rift valley fever (RVF) is a mosquito-borne disease of animals and humans. Although RVF outbreaks are usually reported at 5-15-year intervals in sub-Saharan Africa, Zambia has experienced an unusually long inter-epizootic/-epidemic period of more than three decades. However, serological evidence of RVF virus (RVFV) infection in domestic ruminants during this period underscores the need for comprehensive investigation of the mechanisms of virus perpetuation and disease emergence. Mosquitoes (n = 16,778) captured from eight of the ten provinces of Zambia between April 2014 and May 2019 were pooled (n = 961) and screened for RVFV genome by a pan-phlebo RT-PCR assay. Aedes mosquito pools (n = 85) were further screened by nested RT-PCR assay. Sera from sheep (n = 13), goats (n = 259) and wild ungulates (n = 285) were screened for RVFV antibodies by ELISA while genome detection in pooled sera (n = 276) from domestic (n = 248) and wild ungulates (n = 37) was performed by real-time RT-PCR assay. To examine the association between the long inter-epizootic period and climatic variables, we examined El Niño-Southern Oscillation indices, precipitation anomalies, and normalized difference vegetation index. We then derived RVF risk maps by exploring climatic variables that would favor emergence of primary RVFV vectors. While no RVFV genome could be detected in pooled mosquito and serum samples, seroprevalence was significantly high (OR = 8.13, 95% CI [4.63–14.25]) in wild ungulates (33.7%; 96/285) compared to domestic ruminants (5.6%; 16/272). Retrospective analysis of RVF epizootics in Zambia showed a positive correlation between anomalous precipitation (La Niña) and disease emergence. On risk mapping, whilst northern and eastern parts of the country were at high risk, domestic ruminant population density was low (< 21 animals/km²) in these areas compared to low risk areas (>21 animals/km²). Besides evidence of silent circulation of RVFV and the risk of disease emergence in some areas, wildlife may play a role in the maintenance of RVFV in Zambia.

Rift valley fever (RVF) is an important mosquito borne disease of humans and ruminants. RVF is endemic in sub-Saharan Africa where disease outbreaks are frequently reported in humans and animals. For RVF outbreaks to occur, there has to be presence of the host (animals or humans) and favorable climatic conditions that favor emergence of RVF virus vectors (mosquitoes). Understanding this complex interaction enables us to predict future disease outbreaks and map RVF high risk areas. Above normal rainfall and floods will usually trigger RVF outbreaks. In this study, we conducted surveillance for RVF in mosquitoes, domestic and wild ruminants. We then examined climatic conditions that may have been responsible for past RVF outbreaks and the unusually (>30 years) long inter-epizootic period. Finally, we derived RVF risk maps for Zambia using a combination of climatic variables. We found evidence of RVF infection in both wild and domestic ruminants while there was a positive correlation between past RVF outbreaks and above-normal rainfall. On risk mapping, we found favorable conditions (i.e. high rainfall and risk of flooding) for RVF emergence in northern and eastern parts of the country. Studies like this are important in planning surveillance and disease control programs.